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2005

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Articles 31 - 39 of 39

Full-Text Articles in Other Environmental Sciences

Is Degradation A Major Problem In Semi-Desert Environments Of The Gobi Region In Southern Mongolia?, Karsten Wesche, Vroni Retzer Jan 2005

Is Degradation A Major Problem In Semi-Desert Environments Of The Gobi Region In Southern Mongolia?, Karsten Wesche, Vroni Retzer

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

This paper tests predictions derived from the non-equilibrium theory of rangeland science. Data were collected in livestock enclosures situated in the relatively moist desert steppes of the Gobi Gurvan Saykhan region of southern Mongolia from 2000 to 2003. Plant community composition and species’ richness in enclosures showed clear differences between years, but these were equally strong in ungrazed controls. Thus, changes were mainly attributed to differences in precipitation between years as opposed to grazing, as no significant effects thereof were detected. This was also confirmed by data on above-ground standing biomass. This changed tremendously over the years, with differences between …

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The Communicator, Volume 1, Issue 2, September 2005 Jan 2005

The Communicator, Volume 1, Issue 2, September 2005

The Communicator: News from the Nebraska Cooperative Fish and Wildlife Research Unit

People New Assistant Unit Leader Current Research Landowner Incentives Program (LIP) Amphibians in the Rainwater Basin Resilience in Ecosystems Cross-Scale Structure in Ecosystems Diversity and Ecological Functions: Pollination Future Research Projects Impact of White Perch on Walleye Spatial Risk Assessment of Invasive Species Impacts on Native Species in Nebraska Graduate Students (Donald (Don) Wardwell; Elizabeth (Beth) Forbus; Aaron Lotz) EVENTS Conferences/Meetings

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Auditory Brainstem Responses In The Eastern Screech Owl: An Estimate Of Auditory Thresholds, Elizabeth F. Brittan-Powell, Bernard Lohr, D. Caldwell Hahn, Robert J. Dooling Jan 2005

Auditory Brainstem Responses In The Eastern Screech Owl: An Estimate Of Auditory Thresholds, Elizabeth F. Brittan-Powell, Bernard Lohr, D. Caldwell Hahn, Robert J. Dooling

United States Geological Survey: Staff Publications

The auditory brainstem response (ABR), a measure of neural synchrony, was used to estimate auditory sensitivity in the eastern screech owl (Megascops asio). The typical screech owl ABR waveform showed two to three prominent peaks occurring within 5 ms of stimulus onset. As sound pressure levels increased, the ABR peak amplitude increased and latency decreased. With an increasing stimulus presentation rate, ABR peak amplitude decreased and latency increased. Generally, changes in the ABR waveform to stimulus intensity and repetition rate are consistent with the pattern found in several avian families. The ABR audiogram shows that screech owls hear best between …

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An Assessment Of Key Aspects Of Warm And Cool Season Severe Flash Flooding In The Southern Appalachians, W. M. Baldwin, R. Mahmood Jan 2005

An Assessment Of Key Aspects Of Warm And Cool Season Severe Flash Flooding In The Southern Appalachians, W. M. Baldwin, R. Mahmood

School of Natural Resources: Faculty Publications

No abstract provided.

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The Evolution Of A Warm Season Severe Eastern Kentucky Flash Flood, C. Henry, R. Mahmood, C. Smallcomb, M. Mclane, D. Champlin Jan 2005

The Evolution Of A Warm Season Severe Eastern Kentucky Flash Flood, C. Henry, R. Mahmood, C. Smallcomb, M. Mclane, D. Champlin

School of Natural Resources: Faculty Publications

No abstract provided.

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High Dispersal In A Frog Species Suggest That It Is Vulnerable To Habitat Fragmentation, W. Chris Funk, Allison E. Greene, Paul Stephen Corn, Fred W. Allendorf Jan 2005

High Dispersal In A Frog Species Suggest That It Is Vulnerable To Habitat Fragmentation, W. Chris Funk, Allison E. Greene, Paul Stephen Corn, Fred W. Allendorf

United States Geological Survey: Staff Publications

Global losses of amphibian populations are a major conservation concern and have generated substantial debate over their causes. Habitat fragmentation is considered one important cause of amphibian decline. However, if fragmentation is to be invoked as a mechanism of amphibian decline, it must first be established that dispersal is prevalent among contiguous amphibian populations using formal movement estimators. In contrast, if dispersal is naturally low in amphibians, fragmentation can be disregarded as a cause of amphibian declines and conservation efforts can be focused elsewhere. We examined dispersal rates in Columbia spotted frogs (Rana luteiventris) using capture– recapture analysis …

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Population Structure Of Columbia Spotted Frogs (Rana Luteiventris) Is Strongly Affected By The Landscape, W. Chris Funk, Michael S. Blouin, Paul Stephen Corn, Bryce A. Maxell, David S. Pilliod, Stephen Amish, Fred W. Allendorf Jan 2005

Population Structure Of Columbia Spotted Frogs (Rana Luteiventris) Is Strongly Affected By The Landscape, W. Chris Funk, Michael S. Blouin, Paul Stephen Corn, Bryce A. Maxell, David S. Pilliod, Stephen Amish, Fred W. Allendorf

United States Geological Survey: Staff Publications

Landscape features such as mountains, rivers, and ecological gradients may strongly affect patterns of dispersal and gene flow among populations and thereby shape population dynamics and evolutionary trajectories. The landscape may have a particularly strong effect on patterns of dispersal and gene flow in amphibians because amphibians are thought to have poor dispersal abilities. We examined genetic variation at six microsatellite loci in Columbia spotted frogs (Rana luteiventris) from 28 breeding ponds in western Montana and Idaho, USA, in order to investigate the effects of landscape structure on patterns of gene flow. We were particularly interested in addressing …

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Late-Holocene Flooding And Drought In The Northern Great Plains, Usa, Reconstructed From Tree Rings, Lake Sediments And Ancient Shorelines, M. D. Shapley, W. C. Johnson, D. R. Engstrom, W. R. Osterkamp Jan 2005

Late-Holocene Flooding And Drought In The Northern Great Plains, Usa, Reconstructed From Tree Rings, Lake Sediments And Ancient Shorelines, M. D. Shapley, W. C. Johnson, D. R. Engstrom, W. R. Osterkamp

United States Geological Survey: Staff Publications

During the AD 1990s the Waubay Lakes complex in eastern South Dakota experienced historically unprecedented high water levels. Property damage from this flooding led to an examination of the occurrence of past pluvial episodes and their relation to climate. A lOOO-year hydroclimate reconstruction was developed from local bur oak (Quercus macrocarpa) tree-ring records and lake-sediment cores. Analysis of lake shoreline and drainage features provides late-Quaternary geomorphic context for this high-resolution record. Tree-ring width and shell geochemistry of the ostracode Candona rawsoni show marked coherence, indicating synchronous responses to moisture balance in vegetation and lake salinity; geomorphic evidence …

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Spatial Relationships Of Grassland Net Ecosystem Carbon Dioxide Exchange In A First-Order Agricultural Basin In Southern Ontario, Patrick S. Chahil Jan 2005

Spatial Relationships Of Grassland Net Ecosystem Carbon Dioxide Exchange In A First-Order Agricultural Basin In Southern Ontario, Patrick S. Chahil

Theses and Dissertations (Comprehensive)

This study quantified the midday (10:00 – 16:00) summer source/sink CO2 relationships of various land-use types, particularly grass-dominated riparian areas, using dynamic chamber techniques, while evaluating the relative contribution of root and microbial components towards the overall soil respiration. The influence of nearby agriculture and was related to elevated N and P, which were 40 and 1000% larger, respectively. A site adjacent to cropped fields showed similar (within 8%) study averaged soil respiration as an open grassland site, but 22% lower soil respiration than a riparian site 250-300 m downstream, which is adjacent to an open grassland fallow. A maple …

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